Umm Salamah (May Allah be pleased with her) said

I was with the Messenger of Allah (ﷺ) along with Maimunah (May Allah be pleased with her) when Ibn Umm Maktum (May Allah be pleased with him) (who was blind) came to visit him. (This incident took place after the order of Hijab). The Prophet (ﷺ) told us to hide ourselves from him (i.e., observe Hijab). We said: "O Messenger of Allah (ﷺ), he is blind and is unable to see us, nor does he know us." He replied; "Are you also blind and unable to see him?"

[Abu Dawud and At- Tirmidhi].